Starter gearing



Feb. 23, 1943. T, JACKSON 2,311,944

STARTER GEARING Filed April '7, 19-41 3 Sheets-Sheet 1 QT ma 59 Feb. 23, 1943. T. JACKSON STARTER GEARING Filed April 7, 1941 3 Sheets-Sheet 2 I N VE N TOR. Zomys aikson fitbl-ngg.

Feb. 23,1943. T. JACKSON Filed April '7, 1941 3 Sheets-Sheet 5 Patented Feb. 23, 1943 STARTER GEARING Thomas Jackson, North Muskegon, Mich., assignor to Continental Motors Corporation, Detroit, Mich., a corporation of Virginia Application April 7, 1941, Serial No. 387,146

Claims.

My invention relates to aircraft internal combustion engines and more particularly to the accessory gear mechanism and assembly.

Much difficulty has in the past, been encountered in providing starter assemblies for aircraft engines, and more particularly starters which may be economically manufactured and serviced. With aircraft engines of the type employed in training planes and for the many light economical planes, the ap lication of a starter thereto presents many difficulties. The starter, most generally used, is relatively heavy and complex, and is not very economical to install or service. Such starters have never been produced on a heavy production basis and, naturally, the price is rather high. The standard 6 or 12 volt starter as employed in heavy production in the automotive industry and other allied applications have not, heretofore, been suitable due more particularly to the inability of assembling such a starter with the engine because, among other difficulties, it has heretofore been impractical if not impossible to incorporate the required speed reduction mechanism between the starter and crankshaft. One of the objects of my present invention is to provide a starting mechanism and assembly which includes a multiple speed reduction means between the starter and crankshaft, this being preferably accomplished by means of a compound intermediate gear, which has made it possible therefore to start aircraft internal combustion engines of the character described by means of a starter of the 6 or 12 volt type, which starters may be classified in general as an automotive type starter, which is available at an economical price, is easily assembled to the engine, and may be serviced at minimum expense.

Another object of my present invention is to provide an improved starting mechanism for an aircraft engine of the character described by incorporating a compound intermediate reduction gear between the starter and crankshaft, and. providing readily actuable means for shifting said intermediate gear into and out of engagement with the crankshaft starter gear.

Still another object of my present invention is to provide an improved starter mechanism of the character described and for the purpose specified, in which various novel mechanical features are incorporated therein, which facilitate assembly, provide economical manufacturing costs, and which may be readily serviced with a minimum of time and labor.

A further object of my present invention relates to the accessory mechanism in general and more particularly to an improved oil pump assembly and drive.

Still further objects of my present invention relate to various features and structural details, which result in the construction of an accessory gear case assembly of minimum size and weight, and one which may be readily assembled to an aircraft internal combustion engine most economically, and which can be readily and economically serviced.

For a more detailed understanding of my invention reference may be had to the accompanying drawings illustrating the various features of my improved accessory gear mechanism and assembly, and in which:

Fig. l is a rear elevational view of the engine showing the various accessories assembled therewith,

Fig. 2 is a vertical sectional view through the rear end engine construction and taken substantially on the line 2-2 of Fig. 1,

Fig. 3 is a detailed sectional view of the starter driving mechanism taken substantially on the line 33 of Fig. 2, and

Fig. 4 is a sectional view illustrating the oil pump construction and drive, taken substantially on the line 44 of Fig. 2.

I have chosen for purposes of illustration to illustrate my present invention in connection with a conventional aircraft internal combustion engine having a crankcase structure Ill, which includes a rear transverse wall portion H provided with a suitable bearing means for supporting the engine crankshaft l2, cam shaft [3 and other associated devices such as the stub shaft or pilot shaft I 4. An accessory gear housing is bolted or otherwise secured to the crankcase l0 and it will be noted that this gear housing is preferably secured to the rear end face of the crankcase, and is of a minimum thickness by reason of the compact assembly of the various accessory gears housed therein.

Said accessory gear housing I5 is preferably open as at l6 for the drainage of lubricant into an oil sump (not shown) attached to the underside of the engine and gear housing. The rear face of the gear housing is machined in accordance with predetermined design to provide a starter pad ll, to which a conventional 6 or 12 volt starter I8 is secured by means of bolts or other suitable fastening devices I9.

It will be observed that the starter preferably carries the end plate 20 secured against the :pad I1, and which is provided with a depending ear portion 2| that carries a bearing 22 for supporting the shank 23 of the shiftable intermediate compound reduction gear 24. The shank 23 of this compound gear is engaged by an arm 25, which is actuated in timed relation with the electric starter control 27. The arm 25 is manually shifted or rocked to push on said shank 23 and to then cut in the electric switch or control 21. Thus, on starting the said starter, the compound gear 24 is shifted axially into engagement with the crankshaft starter gear 3i). More particularly, this compound gear comprises a hub 3i preferably formed integral with the shaft or shank 23, and carries the large diameter gear 32 which is in mesh with the starter gear 33. As the intermediate compound gear is axially shifted to the dotted position shown in Fig. 2 it will be noted that the large diameter gear 32 remains in mesh with the starter gear 33. Said hub 3| of the com-pound gear carries a small gear extension 34 which is recessed as at 35 to receive the stub shaft or pilot shaft it. As this compound gear is shifted into the dotted line position (see Fig. 2) the small gear 35 is moved into meshing engagement with the crankshaft starter gear 30, which is preferably secured to the crankshaft 12 by means of bolts 35. A spring or other suitable resilient means of conventional construction, which is designated 37, is operable to retract the compound gear or move the same out of engagement with the crankshaft starter gear when the electrical current to the starter is switched off.

It will be observed that Various combinations of gears assembled within the gear housing in accordance with the principles of my invention may be employed to vary the speed reduction between the starter and crankshaft, but I. find that very satisfactory results can be obtained by employing a total speed reduction of approximately 30 to 1 between the starter and crankshaft, and such a reduction makes it possible to employ a conventional production starter of the standard 6 or 12 volt type herein illustrated and this type of starter is generally classified as a starter of the automotive type. starting mechanism may be advantageously used in the aeronautical field and the total overall weight including the 6 or 12 volt battery is less than the present day starter.

The crankshaft starter gear is of the compound type, and also provides a gear 56 of smaller pitch diameter than gear 30, this gear 38 meshing with a gear 4! secured by bolts 52 to the flange 43 carried by the cam shaft l3. This cam shaft gear 4| carries integrally therewith an internal gear 44, to which may be meshed the driven gear 45 associated with the generator at and preferably connected with the generator armature shaft by a flexible coupling tea.

Axially located on the cam shaft gear is a recess 4311 which is flattened or squared end i! of the oil pump driving shaft 43 incorporated with the oil pump structure 49, and preferably formed integral with the driving gear i? of the oil pump and: supported in usual bearings in the oil "pump housing 5!. The driven gear 52 of the oil' pump is provide-d with a shaft extension 53 projecting rearward-1y through the housing i5 and constructed for driving connection with an engine accessory, such as the tachometer a l.

It will thus be observed that the oil pump projects inwardly of the internal ring gear as and the driving gear of the oil pump has a shaft extension which is directly driven by the This type. of v cam shaft gear. The oil p p drivingi ear is :75

thus axially aligned with the cam shaft and is assembled relatively closely adjacent to the cam shaft gear thus providing a very compact assembly, and the whole accessory gear assembly and housing is thus of minimum weight and size and particularly applicabl to an aircraft engine.

The particular assembly also incorporated gear mountings which support the various accessory mechanism in such a way that the accessory gears all rotate about axes extending parallel to the crankshaft axis. Incidentally, it will be observed that the magneto gears and 60a are in constant mesh with and driven by the cam shaft gear 4 I.

Although I have illustrated but one form of my invention and have described in detail but a single application thereof, it will be apparent to those skilled in the art to which my invention pertains, that various modifications and changes may be made therein without departing from the spirit of my invention or from the scope of the appended claims.

I claim:

1. In an aircraft internal combustion engine, a crankcase, a crankshaft supported by the crankcase and carrying a crankshaft starter gear, a gearcase secured to the crankcase for housing accessory gear mechanism, a starter removably carried by said gear case and including a cover plate and a starter gear, and multiple reduction gearing supported within said gear housing and connecting said starter gear with said crankshaft starter gear, said multiple reduction gearing including an intermediate compound gear slidably and rotatably supported by said cover plate and manually actuated to move into and out of engagement with said crankshaft starter gear while remaining in mesh with said starter gear at all times, and means carried by the crankcase for piloting the sliding intermediate gear as same is moved into and out of engagement with said crankshaft starter gear, said intermediate compound gear comprising a unitassembly with said starter.

2; In an aircraft internal combustion engine, a crankcase, a crankshaft supported by said crankcase and carrying a crankshaft starter gear, a gear case secured to said crankcase and having an opening, a gear case cover closing the opening in said gear case and supporting a starter provided with a starter gear projecting within said gear case, a compound intermediate spur gear slidably and rotatably supported by said-gear case cover and meshing with the starter gear, an actuating means carried bysaid starter and manually operable to actuate the electric control for said starter and to axially shift said compound intermediate into meshing engagement with the crankshaft starter gear while maintaining same constantly in mesh with said starter gear, and a fixed stud carried by the crankcase for piloting said compound intermediate spur gear as same is axially shifted into and out of engagement with the crankshaft starter gear.

3. In an aircraft internal combustion engine, a crankcase, a crankshaft supported by said crankcase and carrying a crankshaft starter gear, a gear case secured to said crankcase and having an opening, a gear-case cover closing the opening in said gear case and supporting a starter provided with a starter gear projecting within said gear case, a compound intermediate spur gear slidably and rotatably supported by said gear case cover and meshing with the starter gear, an actuatingmeans carried by said starter and manually operable to actuate the electric control for said starter and to axially shift said compound intermediate into meshing engagement with the crankshaft starter gear while maintaining same constantly in mesh with said starter gear, and a fixed stud carried by the crankcase for piloting said compound intermediate spur gear as same is axially shifted into and out of engagement with the crankshaft starter gear, said compound in ermediate spur gear provided with a cylindrical recess into which said stud is telescopically seated, said compound intermediate spur gear rotatably supported in part by said pilot stud.

4. In an aircraft internal combustion engine, a crankcase, a crankshaft supported by said crankcase and carrying a crankshaft starter gear, a gear case secured to said crankcase and having an opening, a gear case cover closing the opening in said gear case and supporting a starter provided with a starter gear projecting within said gear case, a compound intermediate spur gear slidably and rotatably supported by said gear case cover and meshing with the starter gear, an actuating means carried by said starter and manually operable to actuate the electric control for said starter and to axially shift said compound intermediate into meshing engagement with the crankshaft starter gear while maintaining same constantly in mesh with said starter gear, and a fixed stud carried by the crankcase for piloting said compound intermediate spur gear as same is axially shifted into and out of engagement with the crankshaft starter gear, said crankshaft starter gear comprising a compound gear structure directly geared with accessory gear mechanism housed within said gear case.

5. In an aircraft internal combustion engine, a crankcase, a crankshaft supported by said crankcase and carrying a crankshaft starter gear, a gear case secured to said crankcase and having an opening, a gear case cover closing the opening in said gear case and supporting a starter provided with a starter gear projecting within said gear case, acompound intermediate spur gear slidably and rotatably supported by said gear case cover and meshing with the starter gear, an actuating means carried by said starter and manually operable to actuate the electric control for said starter and to axially shift said compound intermediate into meshing engagement with the crankshaft starter gear While maintaining same constantly in mesh with said starter gear, and a fixed stud carried by the crankcase for piloting said compound intermediate spur gear as same is axially shifted into and out of engagement with the crankshaft starter gear, said starter, gear case cover and compound intermediate spur gear removable as a unit from said gear case.

THOMAS JACKSON. 

